Recent economic activities of mass production, mass consumption and mass disposal have been causing global environmental problems such as global warming and depletion of resources. In such circumstances, with the intention of constructing a recycling-oriented society, the Home Appliance Recycling Law was enforced in April, 2001, making it obligatory to recycle used air conditioners, television receivers, refrigerators/freezers, and washing machines.
Conventionally, home appliances no longer required are first crushed at a home appliance recycling factory, and subsequently separated and recovered by material utilizing magnetic force, wind power, vibration, or the like to be reused as resources. In particular, a high recycling rate is achieved for metal materials, by recovering materials such as iron, copper and aluminum on a per-material basis at high purities using a gravity separator or a magnetic separator.
On the other hand, as for resin materials, polypropylene (hereinafter referred to as PP) with a low specific gravity is separated from materials with high specific gravities through gravity separation utilizing water and is recovered at a relatively high purity. However, the gravity separation utilizing water is considerably disadvantageous in that a large amount of effluent is produced and in that polystyrene (hereinafter referred to as PS) and acrylonitrile butadiene styrene (hereinafter referred to as ABS) which have similar specific gravities cannot be separated. Furthermore, in recent years demand for filler-added polypropylene with a high specific gravity has expanded, and the conventional gravity separation is incapable of meeting the demand.
Separating methods taking into consideration the aforementioned disadvantages regarding the recycling of resin materials are proposed in Japanese Utility Model Laid-Open No. 4-126822 and Japanese Patent Laid-Open No. 2002-234031.
The separating method proposed in Japanese Utility Model Laid-Open No. 4-126822 utilizes a difference between melting temperatures of two types of resins to be separated, and separates the two types of resins from each other by heating a pair of peripheral moving surfaces made of heat-resistant steel so as to reach the intermediate temperature of the melting temperatures of the two types of resins to be separated, and passing the two types of resins to be separated through a gap between the heated peripheral moving surfaces to allow only one of the resins whose melting temperature is lower to adhere to the heated peripheral moving surfaces.
Furthermore, the separating method proposed in Japanese Patent Laid-Open No. 2002-234031 utilizes a difference in dielectric loss between resin materials. The separating method performs separation by subjecting a separation object including a mixture of at least two types of resins to dielectric heating with the application of an electromagnetic wave or the like, and utilizing a difference between the melting characteristics of the resin materials based on a difference between the heating properties of the respective resin materials. The separating methods described above do not produce effluent and are not affected by the specific gravities of the resin materials.